Pentagastrin

A synthetic polypeptide and CCK2 receptor agonist; binds selectively to CCK2 in guinea pig brain over CCK1 receptors in rat pancreas (IC50s = 11 and 1,100 nM, respectively); increases calcium influx and polyphosphoinositide turnover in rat GH3 pituitary cells (EC50s = 23 and 3.9 nM, respectively); increases histidine decarboxylase activity in mucous and endocrine cell-enriched isolated rabbit fundic mucosal cells (EC50 = 2.9 nM); induces contraction of isolated pig ileum smooth muscle cells in vitro (EC50 = 30 pM); increases gastric acid and pepsin secretion in conscious cats in vivo (ED50s = 1.29 and 57.3 nmol/kg2 per hour, respectively)